Prosthetic Attachment Device for Osseointegrated Implants

ABSTRACT

Technology is described which can provide a quick disconnect and overload protection mechanism for a prosthetic limb that is used with an osseointegrated percutaneous post. The technology can provide a way to easily don and doff a prosthetic limb. This quick disconnect may also provide a resettable torsional overload protection mechanism and/or a fusible link that may act to protect the osseointegrated percutaneous post from both axial and bending over-loads.

PRIORITY DATA

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 63/185,810, filed May 7, 2021, which isincorporated herein by reference.

BACKGROUND

Prostheses (or prosthetics) are artificial devices that replace humanbody parts (e.g., fingers, hands, arms, legs). Generally, prostheses maybe used to replace human body parts lost by injury or missing frombirth. Prostheses are typically connected to a person's body using asocket that can receive a remnant limb.

Prostheses can also be connected to a person's body using anosseointegrated implant where a metal implant may be used which isimplanted into the bone of the remnant limb and passes through the skinto the outside of a person's body. A percutaneous post may be implanted(osseointegrated) into the remnant limb of an individual with limb-loss,and the percutaneous post is used to attach a prosthesis to theamputee's remnant limb. In some situations, a porous titanium coating onthe implant is used to enable a person's skin and bone to connect intothe implant and secure the osseointegrated implant or percutaneous post.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an isometric side view of an example of a quick-disconnectand overload protection device for prosthesis users.

FIG. 1B illustrates an axial cross section of an example of thequick-disconnect and overload protection device.

FIG. 2 illustrates an example of a cut away of the top cover that may berotated clockwise to lock and counter clockwise unlock the prosthesisfrom a percutaneous post.

FIG. 3A illustrates an example of a ring-shaped spring with detents androllers.

FIG. 3B illustrates an example perspective cut away view showing therollers and a carousel for the rollers.

FIG. 4 illustrates an example of a fusible link secured to a pyramid bya screw.

DETAILED DESCRIPTION

Reference will now be made to the examples illustrated in the drawings,and specific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of thetechnology is thereby intended. Alterations and further modifications ofthe features illustrated herein, and additional applications of theexamples as illustrated herein, which would occur to one skilled in therelevant art and having possession of this disclosure, are to beconsidered within the scope of the description.

A technology is described which can provide a quick disconnect andoverload protection mechanism for a prosthetic limb that is used with anosseointegrated percutaneous post. The technology may enable a user toeasily don and doff a prosthetic limb. This overload protection devicemay also provide a resettable torsional overload protection mechanismand a fusible link which is “drum-like”. The fusible link may act toprotect the osseointegrated percutaneous post from both axial andbending over-loads.

FIG. 1A illustrates an isometric view of an example of thequick-disconnect and overload protection device. A percutaneous postsupport and quick disconnect assembly with a cap 102 may be provided toallow the percutaneous post 101 to be inserted into and supported by thequick disconnect assembly. A torsional resettable overload mechanism 103with a housing 120 having a first end 122 and a second end 124 isincluded to provide torsional breakaway capability in order protect theprosthesis use from torsional forces. A fusible link 104 is provided foraxial and bending overload protection.

FIG. 1A further illustrates that the example assembly may provide aquick disconnect for donning and doffing of the prosthesis from theosseointegrated percutaneous post. This example device or system allowsthe prosthesis user to remove the prosthesis easily by rotating a cap102 counter clockwise and locking the cap 102 in place by rotating thecap 102 clockwise.

In one configuration, the percutaneous post support may be a permanentpost support for the overload support device and may be fasteners suchas a threaded fastener, a rivet fastener, an integrated bolt system,locking pins, fixed fasteners, fixed threaded fasteners, or otherstructures for permanently attaching the percutaneous post to theoverload protection device. As discussed further in this description,the percutaneous post support may also be an attachable and removablesystem that can be disconnected and re-attached by the amputee. This mayinclude a quick disconnect, a lever and pin system, a tool manipulateddisconnect or another type of amputee controllable connect system.

FIG. 1B illustrates an axial cross section of one example configurationof the quick-disconnect and overload protection device. The percutaneouspost support and quick disconnect assembly 102 are illustrated. Thetorsional resettable overload mechanism 103 is also depicted. Thefusible link 104 is illustrated which can provide axial and bendingoverload protection to a prosthesis user. The fusible link 104 may be“drum-like” because the fusible link is flexible like a drum head butthe fusible link may fracture or separate under sufficient load so thatthe prosthetic limb will separate from the percutaneous post supportupon the occurrence of a load that might injure the user and the user'sremnant bone. A pyramid attachment 105 may allow for angular alignmentof the prosthesis and attachment of a prosthetic hand, hook, tool or asimilar type of attachment. In one example, the pyramid attachment 105may be attached with a threaded fastener. The pyramid attachment may beattached using a pin assembly, nails, bolts, rivets, adhesives, or otherattachment assemblies.

The pyramid may be an example of one prosthetic attachment structure butother types of structures or assemblies may be used to attach aprosthetic to the load protection device. For example, a pin system,ratcheting system or other system may be used to connect a prostheticlimb to the load protection device.

FIG. 2 shows a partial cut away of the top cover 105 that may be rotatedclockwise to lock and counter clockwise unlock the prosthesis (e.g., ahand or foot prosthesis) from the percutaneous post 101. As the topcover 105 rotates, the top cover 105 engages compliant or spring lockingmembers 108 into a locking groove 106 in one end of the percutaneouspost 101. In other configurations, the quick disconnect may becontrolled using a lever that moves a blade, or a button can be used torelease a blade, ratchet and pawl, pin or similar locking assembly fromthe percutaneous post. Generally speaking, the quick disconnect may holdthe percutaneous post in place with respect to the housing or device inone state, and the quick disconnect may disengage the percutaneous postwith respect to the housing or device in a second state.

This quick disconnect system may provide an attachment that minimizesthe play or backlash between the quick disconnect system and thepercutaneous post 101. The compliant members 108 (e.g., compliantmaterial or spring-loaded cams) may securely engage in a groove 106 onthe end of the percutaneous post. When an excessive amount of force isapplied to the percutaneous post in the axial direction, the springsprovide flexibility to adjust for that force. In some situations, wherethe axial force is great enough (i.e., a little less force than willinjure the amputee), the percutaneous post may dis-engage from quickdisconnect system. A pyramid or lock blocks (not seen in FIG. 2 but seeFIG. 1) may be used to attach the prosthetic limb to the quickdisconnect system, and the lock blocks may be tapered or un-tapered.

FIG. 3A illustrates a ring spring 109 with detents 110 and rollers 111.The ring spring 109 may be secured to the proximal percutaneous post bymeans of slots and the quick disconnect section of the device. Thedistal section of the overload protection device may be secured to theprosthesis by means of the pyramid.

The rollers 111 may be attached to the distal section of the device.When the prosthesis is over-loaded in torsion, the prosthesis, distalsection of the device, and the rollers rotate when the load issufficient to distend the ring spring 109 and allow the rollers to rollout of detents 110 (i.e., a roller detent) and roll around the interiorsurface of the ring spring until another detent is reached. Slots 113(i.e., spring slots) are cut in the ring spring to enhance the ring'sflexibility and/or to assist with attaching to the ring spring 109 tothe quick disconnect assembly 102. The ring spring 109 may be attachedto the base ring 117 or formed as an integral part of the base ring 117.A ring spring diameter and detents (e.g., detent depths) may be set suchthat for a desired torsion, the ring spring 109 distends elastically,and the rollers roll or move out of the detents for breakawayprotection. The ring spring diameter and detents can also be set todistend elastically to allow for resetting of the rollers in the detentsafter a breakaway occurs.

In one example of a prosthesis used with this technology, the prosthesismay be a prosthetic hand and/or wrist. In second prosthesis example, theprosthesis may be a foot and/or ankle.

The ring spring 109 or circular spring may also be changed out based onthe amount of torsion resistance desired. The ring spring may be removedand replaced with a thinner or thicker ring wall, as desired. A thickerring spring wall may increase the torsion force for the rollers tobreakaway and a thinner ring spring wall can do the opposite. Similarly,the material of the ring spring 109 may be various materials and thematerial used can affect the flexibility of the ring. For example, thering may be made of metal, plastic, composite or another suitable springmaterial.

The resettable torsional over-load protection configuration for theprosthetic attachment device can limit the load moment about the axis ofthe percutaneous post to prevent injury of the interface to the remnantbone of the prosthesis user. As mentioned before, this load limitingfeature is accomplished using a ring spring 109 which has a specifiedstiffness (e.g., thickness or material type). Furthermore, the ringspring 109 can have one or more detents 110 (e.g. three or five detents)in which rollers 111 are positioned prior to the prosthesis being loadedwith torsional loads. When unacceptable torsional loads are applied tothe prosthesis, the prosthesis transmits torsional loads to the ringspring 109 through the rollers 111, such that the rollers 111 distendthe ring 109 by rolling up the ramp of the detents 110 which may allowthe prosthesis to rotate without applying unacceptable torsional loadsto the remnant limb.

Rollers 111 that have moved can be reset by the prosthesis user bymanually rotating the prosthesis (e.g., an arm, hand or foot) linked tothe rollers 111 back into the detents 110. The entry ramp to the detent110 may be set at an angle that makes resetting comparatively easy.

FIG. 3B illustrates an example perspective cut away view of the overloadprotection device depicting the rollers 111 and a carousel for therollers 111. The carousel has first carousel plate 130 or first rollersupport and a second carousel plate 132 or second roller support. Thecarousel and carousel plates are attached (e.g., rigidly) to the quickrelease housing 102 or quick disconnect. Thus, the carousel is directlyattached to the quick release housing 102. When a load is applied to theprosthesis, the load transfers from the prosthesis to the base of thetorsional overload protect and to the ring spring 113 (which istransparent in this figure). The rollers 111 may act on the ring spring113 and the ring spring 113 can distend to breakaway. The post 101,carousel and carousel plates 130, 132, and rollers 111 act as astationary ground for the breakaway system. The retaining plate 117 (SeeFIG. 1) may act as the second carousel plate 132 or the retaining plate117 may be mounted over the second carousel plate 132.

FIG. 4 shows the fusible link 104 secured to pyramid 105 by means of athreaded screw 114. The fusible link 104 may be considered drum-likewhere the fusible link 104 may be flexible like a drum head but thefusible link may breakaway under sufficient load. A pyramid 105 can besecurely attached to the prosthesis. The fusible link 104 may beattached to the body or housing of the prosthetic attachment device bymeans of screws 115 between a retaining plate 116 and base ring 117. Thefusible link 104 can be designed to protect the percutaneous post andremnant limb from axial and bending overloads.

Referring further to FIG. 4, the fusible link 104 in the prostheticattachment device is designed to break away when axial or bending loadsare applied to the prosthesis that could harm the percutaneous postinterface for the remnant bone of the prosthesis user. The fusible link104 may break along a circumference of the fusible link 104, or thefusible link 104 may break in the center of the fusible link 104 wherethe bolt 114 passes through the fusible link 104. Other types of scoringmay be applied to the fusible link 104 to encourage the fusible link 104to breakaway in defined patterns or at defined force loads.

The fusible link 104 can provide a compact form of bending overloadprotection. This is valuable because a prosthetic limb may be desired tofit within the envelope of a human limb as defined prior to limb loss.The fusible link 104 can provide bending overload protection withoutadding undue length to the prosthesis and enables the prosthetic tobetter fit within the desired hand, wrist and arm envelope.

The fusible link 104 may also be considered a membrane with breakawayproperties. The fusible link 104 can be replaced when a breakaway eventoccurs. Replacing the fusible link 104 is straightforward using handtools to remove and replace the screws or fasteners (e.g., threadedfasteners).

The fusible link 104 can also be tuned for specific loads. The breakawayperformance of the fusible link 104 may be changed by varying thematerial thickness. For example, the material may be metal, plastic,composite material, or other combinations of material. The fusible link104 also provides more reproducible results in terms of a consistentamount of torque that will cause the fusible link 104 to breakaway. Incontrast, elastomeric materials are more difficult to tune and estimateprovided protection as defined by precise weights, thicknesses andstrengths. The fusible link 104 provides a more consistent andreproducible protection mechanism than elastomeric or similar materials.

Since the fusible link creates only small variations in the breakawayforce need to breakaway the fusible link, then a prosthetist can betterdetermine which materials may work well for an amputee. This may meanthat each patient can have a different breakaway strength or forcethreshold selected for them individually. The prosthetist can installdifferent membranes for different patients or user based on the amountof remnant bone, patient's weight, patient's height, activity level,etc. If the fusible link 104 breaks or fails, then the fusible link 104can be replaced by the patient or the prosthetist.

The fusible link 104 may also be able to flex, giving the remnant limb alevel of shock absorption and a natural level of compliance. The fusiblelink 104 may be made from a plastic, composite material, fiberglass orother flexible material. When an axial load is applied to the prostheticlimb, loads are coupled to the fusible link 104. If the axial loadexceeds the acceptable load, then the bolt 114 that extends through thecenter of the “drum-like” member 104 can transfer the forces to thefusible link 104 until the resultant stresses exceed the strength of thematerial and the fusible link 104 ruptures.

To reiterate, when a bending load is applied to the prosthetic limb, amoment transverse to the axis of the prosthetic attachment device may beapplied to bolt 114. The bolt 114 in turn applies a load to the“drum-like” fusible link 104. The fusible link 114 is designed toexhibit a level of compliance that absorbs shock loads to theprosthesis. When bending loads applied to the prostheses exceedacceptable bending loads, the fusible link is designed to break. Inaddition, the fusible link system is designed to be replaceable.

The present technology provides a device for protecting anosseointegrated percutaneous post from overload forces by using aspring-loaded “drum-like” fusible link. Furthermore the “drum-like”fusible link may be clamped at the center of the membrane or drummembrane. Loads are transmitted to the percutaneous post through themembrane and the membrane can break away when overloaded, therebyprotecting the osseointegrated percutaneous post interface with theintact human bone.

The “drum-like” fusible link can have two or more membranes that areused together by layering or joining the membranes together. If onemembrane fails by fracturing, then the second membrane can failplastically such that that the membrane that fails plastically acts likea tether to secure the limb from disconnecting from the prosthesis user.

The “drum-like” fusible link may have the membrane clamped such that anoverload produces primarily shear loads on the membrane. Alternatively,the “drum-like” fusible link may have the membrane clamped such that theclamp slips when torsionally loaded to protect for torsional overloads.For example, the clamping may only be tight enough to resist torsion upto certain force threshold, at which point the fusible link may sliptorsionally. Further, the “drum-like” fusible link may have the membraneclamped such that when a bending load is applied, the membrane fracturesin shear in the direction of bending and deforms plastically ninetydegrees from the direction of bending to secure that limb fromdisconnecting from the prosthesis user.

While FIGS. 1A-5 have illustrated this technology with both the fusiblelink and a ring spring with rollers, a prosthetic limb may use eitherstructure separately. For example, a prosthetist may prescribe a fusiblelink for a prosthetic limb of a first patient that may allow for bendingoverload protection without the ring spring and rollers. A prosthetistmay determine that a second patient needs the ring spring with a rollerfor torsional load protection but this second patient does not need thefusible link. The structure selected may depend on the needs of eachamputee (e.g., the varying bone support for an implant in the amputee).

O-rings or flat seals may be used at part or element interfaces toprotect the overall device from water and dirt damage. For exampleO-rings may be used between any of surfaces joining at least two of: thefusible link, base ring, spring ring, fastener, housing structures, orquick disconnect.

As discussed earlier, length, size and weight are very important forupper limb prosthetics. This technology does not add significant lengthto a prosthetic but can provide full functionality and torsionprotection to an amputee.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more examples. In thepreceding description, numerous specific details were provided, such asexamples of various configurations to provide a thorough understandingof examples of the described technology. One skilled in the relevant artwill recognize, however, that the technology can be practiced withoutone or more of the specific details, or with other methods, components,devices, etc. In other instances, well-known structures or operationsare not shown or described in detail to avoid obscuring aspects of thetechnology.

Although the subject matter has been described in language specific tostructural features and/or operations, it is to be understood that thesubject matter defined in the appended claims is not necessarily limitedto the specific features and operations described above. Rather, thespecific features and acts described above are disclosed as exampleforms of implementing the claims. Numerous modifications and alternativearrangements can be devised without departing from the spirit and scopeof the described technology.

1. A device for protecting a percutaneous post that is osseointegratedin a human limb, comprising: a housing having a first end and a secondend; a quick disconnect coupled to the first end of the housing toremovably support the percutaneous post; a base ring attached to thesecond end of the housing; a fusible link coupled to the base ring; anda fastener coupled to the fusible link to enable fastening of thefusible link to a prosthesis.
 2. The device of claim 1, wherein thequick disconnect is controlled using at least one of a lever, springlocking members, or a button.
 3. The device of claim 2, wherein thequick disconnect retains the percutaneous post in place with respect tothe housing in one state and does not retain the percutaneous post withrespect to the housing in a second state.
 4. The device of claim 1wherein a pyramid attachment is held by the fastener to a center of thefusible link.
 5. The device of claim 2, wherein the fusible link is amembrane.
 6. The device of claim 3, wherein the fusible link isconfigured to breakaway when overloaded to protect an interface of thepercutaneous post with a human bone.
 7. The device of claim 1, whereinthe base ring is attached to a ring spring, which are both connected tothe second end of the housing through a roller or rollers.
 8. The deviceof claim 7, wherein the ring spring has a detent or detents for therollers.
 9. The device of claim 8, wherein a ring spring diameter anddetents are set such that for a desired torsion, the ring springdistends elastically and the roller or rollers roll out of the detentsfor breakaway protection.
 10. The device of claim 9, wherein the ringspring diameter and detent or detents are set to distend elastically toallow for resetting of the rollers after breakaway.
 11. The device ofclaim 1, wherein the fusible link further includes a first membrane anda second membrane, wherein the first membrane fails by fracturing andthe second membrane fails plastically and acts like a tether to securethe prosthesis from disconnecting from a prosthesis user.
 12. The deviceof claim 1, wherein the fusible link is clamped such that an overloadproduces primarily shear loads on the fusible link.
 13. The device ofclaim 1, wherein the fusible link is clamped such that the fusible linkslips when torsionally loaded to protect for torsional overloads. 14.The device of claim 1, wherein the fusible link is clamped such thatwhen loaded with a bending load the fusible link fractures in shear in adirection of bending and plastically at ninety degrees from thedirection of bending to secure a prosthetic attachment fromdisconnecting from a prosthesis user.
 15. The device of claim 1, whereinthe prosthetic attachment structure is a pyramid attachment.
 16. Thedevice of claim 1, wherein the device is water-proof through use ofO-rings at device part interfaces to protect the device from water anddirt damage.
 17. A device for protecting an osseointegrated percutaneouspost in a human limb from overloading when connected to a prosthesis,comprising: a housing having a first end and a second end; apercutaneous post support coupled to the first end of the housing tosupport the osseointegrated percutaneous post; a base ring attached tothe second end of the housing; a fusible link attached to the base ring;and a fastener coupled to the fusible link to enable fastening of thefusible link to a prosthetic attachment structure.
 18. The device ofclaim 17, wherein a pyramid attachment is held by the fastener to acenter of the fusible link.
 19. The device of claim 17, wherein thefusible link is a membrane.
 20. The device of claim 17, wherein thefusible link is configured to breakaway when overloaded to protect aninterface of the percutaneous post with a human bone.
 21. A device forprotecting an osseointegrated percutaneous post in a human limb,comprising: a housing having a first end and a second end; apercutaneous post support coupled to the first end of the housing tosupport the osseointegrated percutaneous post; a ring spring having oneor more detents, wherein the ring spring is attached to the second endof the housing; at least one roller for the ring spring, which iscoupled to a proximal portion of the device; and a carousel attached tothe at least one roller for the ring spring and the percutaneous postsupport.
 22. The device as in claim 21, wherein the carousel is attachedto a prosthesis.
 23. The device as in claim 21, wherein prosthesis is aprosthetic hand.